1. Field of the Invention
This invention relates to well tools, and more particularly to downhole shut-in tools for use in testing subterranian formations such as those penetrated by oil or gas wells.
2. Description of the Related Art
For a number of years, well test tools have been lowered into wells on flexible lines for conducting various types of tests in order to gather physical information which would make possible a reasonable evaluation of the hydrocarbon bearing formation penetrated by the well.
Some of the test tools are electrically powered and have instruments which can sense well characteristics and can generate and send up signals suitable for processing by surface readout equipment. Such tools, understandably, must be lowered into the well on an electrical cable which must remain attached to the test tool. Some others of the test tools are mechanically actuated or partially battery-powered and are run on a conventional single strand wire line (commonly called a "slick line") which remains attached to the test tool. Some of the test tools have the capability of gathering information concerning pressures and/or temperatures, can shut-in the well at a downhole location, and have means for equalizing pressures thereacross prior to retrieving the test tool, but many of these tools have a very small flow capacity. Some of the test tools can be cycled between open and closed as many times as desired; others are installed and then closed, never to be cycled further.
Following is a list of prior art patents with which applicant is familiar.
______________________________________ Re.31,313 3,208,531 4,051,897 4,134,452 4,149,593 4,159,643 4,373,583 4,453,559 4,487,261 4,508,174 4,583,592 ______________________________________
U.S. Pat. No. Re. 31,313 issued to John V. Fredd on July 19, 1983, the original U.S. Pat. No. 4,274,485 having issued to him on June 23, 1981. This patent teaches a test tool which may be installed in a well, after which a probe including pressure sensing means (a recording pressure instrument, or an electronic sensor which will send signals via the electric cable to surface readout equipment for processing, display, and/or recording, for instance, may be run on a flexible line to engage the probe in the test tool for opening and closing the test tool by tensioning or slacking the flexible line. The flexible line must remain attached to the probe in order to actuate the test tool.
U.S. Pat. No. 3,208,531 issued to Jack W. Tamplen on Sept. 28, 1965 and teaches one type of locking device on which test tools such as the test tool of the present invention can be run and installed in a well.
U.S. Pat. No. 4,149,593 issued to Imre I. Gazda and George F. Kingelin on Apr. 17, 1979 and covers a test tool which may be run on a wire line and installed in a well for shutting-in the well or opening it to flow at a downhole location by tensioning and relaxing the wire line. The test tool can be opened and closed any number of times, but the wire line must remain attached to the test tool.
U.S. Pat. No. 4,051,897 issued on Oct. 4, 1977 to George F. Kingelin and teaches a test tool including a lock device anchored in sealed relation in a landing receptacle downhole in a well, and a probe including pressure or temperature sensor transducer and a probe portion having a valve therein, to be lowered into the well on an electrical cable and engaged in the lock device. Then, by tensioning and relaxing the electric cable, the valve in the probe is opened and closed--closed to permit pressure to build therebelow and opened to permit pressures to equalize thereacross preparatory to removing the test tool from the well. The sensor means continuously generates signals which are sent to the surface via the cable for real time readout of the conditions sensed.
U.S. Pat. No. 4,134,452 issued Jan. 16, 1979 to George F. Kingelin. The disclosed invention is an improvement over the invention of U.S. Pat. No. 4,051,897, and although the structure differs in certain details, the test tool accomplished the same purpose.
U.S. Pat. No. 4,159,643 issued to Fred E. Watkins on July 3, 1979 and covers a test tool which is first installed in a well, then a probe including a sensor prong is lowered on an electric cable and latched into the test tool. Tensioning the cable then closes to test tool and signals sent to the surface indicate the pressures below the test tool. The test tool can be actuated from open to closed position only once. At the end of the test, the instrument portion of the sensor prong can be retrieved. Afterwards the prong is retrieve.
U.S. Pat. No. 4,373,583 issued to Fleming A. Waters on Feb. 15, 1983 and covers a test tool installable in a well, the test tool having a valve therein initially in open position and which can be later engaged by a probe and lifted to closed position. The probe can at the conclusion of the test be disconnected from the valve and removed from the well. The valve cannot be reopened although an equalizing valve in the test tool can be opened by a prong on a retrieving tool prior to retrieving the test tool. Thus, the well can be flowed through the initially open valve to record one phase of the well test, then the valve can be closed to stop flow for a second phase of the test during which the instrument records the build-up in pressure below the test tool, but the valve is not intended to be cycled other than being closed just the once. The wire line and probe may be detached from the tool or left attached thereto, as desired, during the shut-in phase of the well test. The present invention is an improvement over the invention disclosed in patent No. 4,373,583 to Fleming A. Waters.
U.S. Pat. No. 4,453,599 issued to John V. Fredd on June 12, 1984 and is cited herein becauses of its teaching of a shutter mechanism which makes it possible to slide a resilient seal ring past a sizeable flow port under conditions of flow without damaging the seal ring. Although a measuring instrument is shown on a flexible line, neither the instrument nor the flexible line is used to actuate the downhole valve which is, instead, pressure actuated.
U.S. Pat. No. 4,487,261 issued to Imre I. Gazda on Dec. 11, 1984 and discloses a test tool run into a well on a flexible line and engaged in a receptacle. When the flexible line is relaxed the test tool opens and when the flexible line is tensioned the test tool closes. The flexible line must remain attached to the test tool in order to actuate it.
U.S. Pat. No. 4,508,174 issued on Apr. 2, 1982 to Neil G. Skinner and David S. Wesson for a downhole test tool which includes a downhole valve and related elements including a receptacle, together with a probe portion including sensor means. The probe is lowerable into the well on a flexible line and is engaged in the receptacle. An upward pull on the flexible line opens a spring-biased slide valve to let formation pressure reach the pressure sensor. Relaxing the flexible line allows a spring to close the slide valve. The well cannot flow at any position of the test valve since the probe fills the receptacle bore. The flexible line cannot be detached from the probe, for this would allow the slide valve to close. The ball valve shown below the test tool is for use in performing drill stem tests and is operated independently of the test tool by other means, such as annulus pressure, the test tool being used to observe pressure build-up beneath the closed ball valve. This invention bears little resemblance to the present invention.
U.S. Pat. No. 4,583,592 issued Apr. 22, 1986 to Imre I. Gazda and Phillip S. Sizer and covers a test tool which may be run into a well for engagement in a downhole receptacle for shutting in the well when the flexible line is tensioned and for opening the well to flow when the flexible line is relaxed. The flexible line must remain attached to the test tool in order to actuate it. The test tool can be cycled between open and closed positions several times before disengaging the landing receptacle, but it can be reengaged as desired for additional cycles. The receptacle comprises telescoping sections which provide an extremely large bypass, thus to provide a flow capacity as great as that of the well tubing.
U.S. Pat. Nos. 3,208,531 to Tamplen, 4,373,583 to Waters, and 4,453,599 to Fredd are incorporated herein by reference thereto for all purposes.
There is not found in the known prior art a well test tool which can be run into a well on a flexible line, installed in a downhole receptacle therein, and cycled as many times as necessary between open and closed positions to allow or prevent flow therethrough, without requiring the presence of the flexible line in the well except as it is required to shift the test tool between open and closed positions.